Add Playwright E2E tests with MSW API mocking

- Playwright + @msw/playwright + @msw/source for OpenAPI-driven mocks
- Chromium-only configuration with Vite dev server integration
- Smoke tests: home page, CTA, navigation
- US-1 tests: validation, event creation flow, localStorage, error handling
- Suppress Node 25 --localstorage-file warning from MSW cookieStore

frontend/e2e/event-create.spec.ts

@@ -0,0 +1,69 @@
+import { http, HttpResponse } from 'msw'
+import { test, expect } from './msw-setup'
+
+test.describe('US-1: Create an event', () => {
+  test('shows validation errors for empty required fields', async ({ page }) => {
+    await page.goto('/create')
+
+    await page.getByRole('button', { name: /create event/i }).click()
+
+    await expect(page.getByText('Title is required.')).toBeVisible()
+    await expect(page.getByText('Date and time are required.')).toBeVisible()
+    await expect(page.getByText('Expiry date is required.')).toBeVisible()
+  })
+
+  test('creates an event and redirects to stub page', async ({ page }) => {
+    await page.goto('/create')
+
+    await page.getByLabel(/title/i).fill('Summer BBQ')
+    await page.getByLabel(/description/i).fill('Bring your own drinks')
+    await page.getByLabel(/date/i).first().fill('2026-04-15T18:00')
+    await page.getByLabel(/location/i).fill('Central Park')
+    await page.getByLabel(/expiry/i).fill('2026-06-15')
+
+    await page.getByRole('button', { name: /create event/i }).click()
+
+    await expect(page).toHaveURL(/\/events\/.+/)
+    await expect(page.getByText('Event created!')).toBeVisible()
+  })
+
+  test('stores event data in localStorage after creation', async ({ page }) => {
+    await page.goto('/create')
+
+    await page.getByLabel(/title/i).fill('Summer BBQ')
+    await page.getByLabel(/date/i).first().fill('2026-04-15T18:00')
+    await page.getByLabel(/expiry/i).fill('2026-06-15')
+
+    await page.getByRole('button', { name: /create event/i }).click()
+    await expect(page).toHaveURL(/\/events\/.+/)
+
+    const storage = await page.evaluate(() => {
+      const raw = localStorage.getItem('fete:events')
+      return raw ? JSON.parse(raw) : null
+    })
+    expect(storage).not.toBeNull()
+    expect(storage).toHaveLength(1)
+    expect(storage[0]).toHaveProperty('eventToken')
+    expect(storage[0]).toHaveProperty('title')
+  })
+
+  test('shows server error on API failure', async ({ page, network }) => {
+    network.use(
+      http.post('*/api/events', () => {
+        return HttpResponse.json(
+          { title: 'Bad Request', status: 400, detail: 'Validation failed' },
+          { status: 400, headers: { 'Content-Type': 'application/problem+json' } },
+        )
+      }),
+    )
+
+    await page.goto('/create')
+    await page.getByLabel(/title/i).fill('Test')
+    await page.getByLabel(/date/i).first().fill('2026-04-15T18:00')
+    await page.getByLabel(/expiry/i).fill('2026-06-15')
+
+    await page.getByRole('button', { name: /create event/i }).click()
+
+    await expect(page.getByRole('alert')).toBeVisible()
+  })
+})